Answer:
A select list
Explanation:
A select list contains data vertically which is only visible when select list is open. On the other hand radio button shows data horizontally and is always visible on screen a large number of data to select from will mess up the user interface. A checkbox has the same problem as radio button.
Text box can also be used but it can be used by user to spam as their are given data user can enter what ever name and spellings of state and province name which will cause inconsistency among data. Therefore select list populated with state/province name is best option.